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EvtRequestImpersonate function

[Applies to UMDF only]

A driver's EvtRequestImpersonate event callback function performs tasks at the requested impersonation level, such as opening a protected file.

Syntax


EVT_WDF_REQUEST_IMPERSONATE EvtRequestImpersonate;

void EvtRequestImpersonate(
  _In_      WDFREQUEST Request,
  _In_opt_  PVOID Context
)
{ ... }

Parameters

Request [in]

A handle to a framework request object that represents the I/O request that requires impersonation.

Context [in, optional]

A pointer to a context that was previously supplied in the WdfRequestImpersonate method. This parameter is optional and can be NULL if a context is not required.

Return value

This function does not return a value.

Remarks

User-Mode Driver Framework (UMDF) does not allow a driver's EvtRequestImpersonate callback function to call any of the framework's object methods. This ensures that the driver does not expose the impersonation level to other driver callback functions or other drivers.

For more information, see Handling Client Impersonation in UMDF Drivers.

Examples

To define an EvtRequestImpersonate callback function, you must first provide a function declaration that identifies the type of callback function you’re defining. Windows provides a set of callback function types for drivers. Declaring a function using the callback function types helps Code Analysis for Drivers, Static Driver Verifier (SDV), and other verification tools find errors, and it’s a requirement for writing drivers for the Windows operating system.

For example, to define an EvtRequestImpersonate callback function that is named MyRequestImpersonate, use the EVT_WDF_REQUEST_IMPERSONATE type as shown in this code example:


EVT_WDF_REQUEST_IMPERSONATE  MyRequestImpersonate;

Then, implement your callback function as follows:


_Use_decl_annotations_
VOID
 MyRequestImpersonate (
    WDFREQUEST  Request
    PVOID  Context
    )
  {...}

The EVT_WDF_REQUEST_IMPERSONATE function type is defined in the Wdfrequest.h header file. To more accurately identify errors when you run the code analysis tools, be sure to add the _Use_decl_annotations_ annotation to your function definition. The _Use_decl_annotations_ annotation ensures that the annotations that are applied to the EVT_WDF_REQUEST_IMPERSONATE function type in the header file are used. For more information about the requirements for function declarations, see Declaring Functions by Using Function Role Types for KMDF Drivers. For information about _Use_decl_annotations_, see Annotating Function Behavior.

Requirements

Minimum support

Windows 8.1

Minimum UMDF version

2.0

Header

Wdfrequest.h (include Wdf.h)

See also

WdfRequestImpersonate

 

 

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